1. Field of the Invention
This invention generally relates to a thermal print head for use in a thermosensitive recording apparatus, a thermal transfer recording apparatus, a copier, a facsimile machine or the like, and, in particular, to a device for driving a thermal print head.
2. Description of the Prior Art
In a thermal print head for use in a thermosensitive recording apparatus, a thermal transfer recording apparatus, or the like, a plurality of heat-producing elements provided in a thermal print head are preheated and selectively activated in accordance with an image signal to be recorded. And, Japanese Patent Laid-open Publication No. 60-67178 teaches a thermal print head drive device to vary the time interval for repeating such a preheat step from a point in time for applying a next drive pulse for recording. However, in such a prior art thermal print head drive device, since each of the plurality of heat-producing elements is preheated irrespective of an image signal, or a dot to be recorded, the preheat energy becomes too high or too low depending on the variation of dots or pixels recorded so that the density of recorded dots or pixels tend to be non-uniform in density.